Five facilities are collaborating on pilot research for an investigation of the psychobiology of depressive lillnesses. The objective of this particular pilot project is to develop algorithms for classifying mental patients and a scoring system for quantifying severity of symptomatology and level of functioning across a number of dimensions. The Schedule for Affective Disorders and Schizophrenia developed uses a structured interview to obtain the information from the patient. It contains both a current and a past history section and comprehensively evaluates a broad range of symptomatology and functioning for purposes of diagnosis and classification as well as measurement of change. The project also examines the distribution of patients in the various classification systems, develops mathematically derived summary scales of broad dimensions and typologies, and compares the relative validities of various extant diagnostic classification systems with more empirically derived dimensional systems. In later years, the full scale collaborative study of affective disorder patients, their first degree relatives, spouses, and normal control subject is undertaken. The longitudinal research involves approximately 965 inpatients and outpatients with the entire gamut of diagnoses related to affective disorders (unipolar, bipolar, schizoaffective, manic, and depressed). Patients are studied every six months for two years after entry into the program, utilizing the Schedule for Affective Disorders and Schizophrenia, the Research Diagnostic Criteria, and intelligence quotient, a personality battery, a personal resources inventory, a medical history form, sociodemographic and upbringing variables, and data related to life events. In addition, about 600 patients (selected by specific diagnoses) are part of a large family study of personality traits and diagnoses of approximately 1,800 family members. Substudies of assortive mating, linkage, and extended pedigrees are performed. Objectives are to validate psychiatric diagnoses by followup, genetic studies, and other correlates; to determine specific modes of transmission of some of these illnesses; to discover variables that predict recovery and remission of an affective episode; and to reexamine typologies of depression.